#include <stdio.h>
#include <stdlib.h>
#include "Types3D.h"
#include "3dsloader.h"

#include <sys/stat.h>

/**********************************************************
 *
 * FUNCTION Load3DS (obj_type_ptr, char *)
 *
 * This function loads a mesh from a 3ds file.
 * Please note that we are loading only the vertices, polygons and mapping lists.
 * If you need to load meshes with advanced features as for example: 
 * multi objects, materials, lights and so on, you must insert other chunk parsers.
 *
 *********************************************************/


long filelength(int f) {
    struct stat buf;

    fstat(f, &buf);

    return (buf.st_size);
}

char Load3DS(obj_type_ptr p_object, char *p_filename) {
    int i; //Index variable

    FILE *l_file; //File pointer

    unsigned short l_chunk_id; //Chunk identifier
    unsigned int l_chunk_lenght; //Chunk lenght

    unsigned char l_char; //Char variable
    unsigned short l_qty; //Number of elements in each chunk

    unsigned short l_face_flags; //Flag that stores some face information

    if ((l_file = fopen(p_filename, "rb")) == NULL) return 0; //Open the file

    while (ftell(l_file) < filelength(fileno(l_file))) //Loop to scan the whole file
        //while(!EOF)
    {
        //getch(); //Insert this command for debug (to wait for keypress for each chuck reading)

        fread(&l_chunk_id, 2, 1, l_file); //Read the chunk header
//        printf("ChunkID: %x\n", l_chunk_id);
        fread(&l_chunk_lenght, 4, 1, l_file); //Read the lenght of the chunk
//        printf("ChunkLenght: %x\n", l_chunk_lenght);

        switch (l_chunk_id) {
                //----------------- MAIN3DS -----------------
                // Description: Main chunk, contains all the other chunks
                // Chunk ID: 4d4d 
                // Chunk Lenght: 0 + sub chunks
                //-------------------------------------------
            case 0x4d4d:
                break;

                //----------------- EDIT3DS -----------------
                // Description: 3D Editor chunk, objects layout info 
                // Chunk ID: 3d3d (hex)
                // Chunk Lenght: 0 + sub chunks
                //-------------------------------------------
            case 0x3d3d:
                break;

                //--------------- EDIT_OBJECT ---------------
                // Description: Object block, info for each object
                // Chunk ID: 4000 (hex)
                // Chunk Lenght: len(object name) + sub chunks
                //-------------------------------------------
            case 0x4000:
                i = 0;
                do {
                    fread(&l_char, 1, 1, l_file);
                    p_object->name[i] = l_char;
                    i++;
                } while (l_char != '\0' && i < 20);
                break;

                //--------------- OBJ_TRIMESH ---------------
                // Description: Triangular mesh, contains chunks for 3d mesh info
                // Chunk ID: 4100 (hex)
                // Chunk Lenght: 0 + sub chunks
                //-------------------------------------------
            case 0x4100:
                break;

                //--------------- TRI_VERTEXL ---------------
                // Description: Vertices list
                // Chunk ID: 4110 (hex)
                // Chunk Lenght: 1 x unsigned short (number of vertices) 
                //             + 3 x float (vertex coordinates) x (number of vertices)
                //             + sub chunks
                //-------------------------------------------
            case 0x4110:
                fread(&l_qty, sizeof (unsigned short), 1, l_file);
                p_object->vertices_qty = l_qty;
//                printf("Number of vertices: %d\n", l_qty);
                for (i = 0; i < l_qty; i++) {
                    fread(&p_object->vertex[i].x, sizeof (float), 1, l_file);
//                    printf("Vertices list x: %f\n", p_object->vertex[i].x);
                    fread(&p_object->vertex[i].y, sizeof (float), 1, l_file);
//                    printf("Vertices list y: %f\n", p_object->vertex[i].y);
                    fread(&p_object->vertex[i].z, sizeof (float), 1, l_file);
//                    printf("Vertices list z: %f\n", p_object->vertex[i].z);
                }
                break;

                //--------------- TRI_FACEL1 ----------------
                // Description: Polygons (faces) list
                // Chunk ID: 4120 (hex)
                // Chunk Lenght: 1 x unsigned short (number of polygons) 
                //             + 3 x unsigned short (polygon points) x (number of polygons)
                //             + sub chunks
                //-------------------------------------------
            case 0x4120:
                fread(&l_qty, sizeof (unsigned short), 1, l_file);
                p_object->polygons_qty = l_qty;
//                printf("Number of polygons: %d\n", l_qty);
                for (i = 0; i < l_qty; i++) {
                    fread(&p_object->polygon[i].a, sizeof (unsigned short), 1, l_file);
//                    printf("Polygon point a: %d\n", p_object->polygon[i].a);
                    fread(&p_object->polygon[i].b, sizeof (unsigned short), 1, l_file);
//                    printf("Polygon point b: %d\n", p_object->polygon[i].b);
                    fread(&p_object->polygon[i].c, sizeof (unsigned short), 1, l_file);
//                    printf("Polygon point c: %d\n", p_object->polygon[i].c);
                    fread(&l_face_flags, sizeof (unsigned short), 1, l_file);
//                    printf("Face flags: %x\n", l_face_flags);
                }
                break;

                //------------- TRI_MAPPINGCOORS ------------
                // Description: Vertices list
                // Chunk ID: 4140 (hex)
                // Chunk Lenght: 1 x unsigned short (number of mapping points) 
                //             + 2 x float (mapping coordinates) x (number of mapping points)
                //             + sub chunks
                //-------------------------------------------
            case 0x4140:
                fread(&l_qty, sizeof (unsigned short), 1, l_file);
                for (i = 0; i < l_qty; i++) {
                    fread(&p_object->mapcoord[i].u, sizeof (float), 1, l_file);
//                    printf("Mapping list u: %f\n", p_object->mapcoord[i].u);
                    fread(&p_object->mapcoord[i].v, sizeof (float), 1, l_file);
//                    printf("Mapping list v: %f\n", p_object->mapcoord[i].v);
                }
                break;

                //----------- Skip unknow chunks ------------
                //We need to skip all the chunks that currently we don't use
                //We use the chunk lenght information to set the file pointer
                //to the same level next chunk
                //-------------------------------------------
            default:
                fseek(l_file, l_chunk_lenght - 6, SEEK_CUR);
        }
    }
    
    fclose(l_file); // Closes the file stream
    return (1); // Returns ok
}
